# Melanotan 2: The Photoprotection and Melanocortin Literature, Summarized > Melanotan 2 is a synthetic melanocortin-receptor agonist studied for UV-independent skin pigmentation. A scholarly digest of the mechanism, the photoprotection evidence, and the documented harms. A direct reading of the primary literature: the MC1R signaling that drives eumelanin synthesis, what the small human studies actually measured, the photoprotection rationale it borrows from a related approved analog, and the harms that case reports have documented. ## The short version **Melanotan 2** is a lab-made copy of a natural body signal that tells skin cells to make pigment. People inject it because it darkens the skin with little or no sun. It is **not** an approved medicine anywhere, and it is not a tanning product — it is an unapproved research chemical, and this site reads it as one. The chemistry is real and well studied: Melanotan 2 switches on receptors (called melanocortin receptors) that drive the skin's natural tanning machinery. The same switches also cut appetite and trigger erections, which is why the effects spread well beyond the skin. The honest catch on the photoprotection idea: most of the strong UV-protection and eumelanin (dark, sun-shielding pigment) evidence comes from a *different, related* molecule, **Melanotan 1 / afamelanotide**, not from Melanotan 2 itself. Real harms are on record too — darkening moles, melanoma case reports, kidney injury, and prolonged painful erections. What people actually report, including the downsides, is on [the effects page](/effects). ## What is Melanotan 2 Melanotan 2 (also written Melanotan II, MT-II, or MT-2) is a synthetic cyclic heptapeptide — a short, ring-shaped chain of seven amino acids — modeled on **alpha-melanocyte-stimulating hormone (alpha-MSH)**, the body's own pigment-signaling hormone [1]. Chemists at the University of Arizona built it in the late 1980s to be far more potent and far more durable than the natural hormone, locking the chain into a ring (a lactam bridge) so that enzymes break it down slowly [1]. The peptide is a *non-selective* agonist of the melanocortin receptors: it switches on all five subtypes (MC1R through MC5R) rather than just one. MC1R sits on pigment cells and governs tanning; MC4R sits in the brain and governs appetite and sexual function. Activating them together is why one compound produces such a spread of effects [1]. The full identifier set — molecular formula C50H69N15O9, CAS 121062-08-6, the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2 — appears on the [melanotan 2 mechanism of action](/mechanism-of-action) page. The original goal was photoprotection: a tan is the skin's defense against ultraviolet light, so a drug that produced one without sun exposure was pitched as a way to lower skin-cancer risk [1]. That rationale is the lens this site leads with — and the section below is candid about how thin the *Melanotan-2-specific* evidence for it actually is. ## What the human literature on Melanotan 2 actually shows The controlled human record for Melanotan 2 is small. The foundational study is a single-blind, alternating-day, placebo-controlled pilot Phase I trial in just three healthy men: subcutaneous Melanotan 2, escalated across five low doses over two weeks, produced measurable facial, upper-body, and buttock pigmentation in two of three subjects **without any UV exposure** [2]. That same trial recorded spontaneous erections lasting one to five hours and mild nausea — the first signal that the compound was never going to be a skin-only drug [2]. (Doses there are reported only as study-design facts; they are not a recommendation, and Melanotan 2 is not approved for human use.) The second controlled study tested 10 men with psychogenic erectile dysfunction in a double-blind crossover design: clinically apparent erections occurred in 8 of 10 men, with mean rigidity duration of 38.0 minutes versus 3.0 minutes on placebo [3]. No Phase II or Phase III trial of Melanotan 2 itself has ever been completed [2][3]. The **photoprotection** evidence base is largely borrowed. The strongest eumelanin and UV-protection data come from the closely related *linear* analog, Melanotan 1 ([Nle4-D-Phe7]-alpha-MSH, marketed as afamelanotide) — including a human study showing the induced tan reflected a genuine rise in photoprotective eumelanin [4], and two Phase 3 trials in erythropoietic protoporphyria that led to afamelanotide's regulatory approval [5]. Those results frame the original rationale, but they describe a *different molecule*. The distinction is drawn carefully on [the tanning page](/tanning). ## Melanotan II, MT2, and the names you will see The same compound circulates under several names, and the literature uses them interchangeably. **Melanotan II** (or MT-II) is the formal research name; **MT2** is the common shorthand; **Melanotan 2** is the most-searched spelling. All three refer to the cyclic alpha-MSH analog described above — not to the linear sibling Melanotan 1 (afamelanotide), and not to the MC4R-optimized derivative bremelanotide (PT-141), both of which are separate, separately-regulated molecules [1]. The term **melanotan** alone is ambiguous in casual use: it has been applied to both analogs and to the unregulated injectable products sold online, which forensic analyses have repeatedly found to be inaccurately labeled or impure [6]. Throughout this site, *Melanotan 2* means the specific cyclic heptapeptide, and the generic compound names are used exclusively. A side-by-side of the analogs lives in [the melanotan 2 research](/research) summary and on [the effects page](/effects). ## How to read this site This is an independent editorial digest of the published Melanotan 2 literature — peer-reviewed studies, case reports, and reviews, summarized in plain English and cited line by line. It is not a clinic, not a vendor, and not a source of medical advice. No human dose is recommended anywhere; where doses appear, they are reported as facts of a specific study's design. The [melanotan 2 mechanism of action](/mechanism-of-action) page covers the receptor biology; [the tanning page](/tanning) covers pigmentation and the photoprotection question; [the research page](/research) collects the key studies; and [the effects page](/effects) gives the frank account of reported benefits and the documented harms. Every quantitative claim maps to a numbered source in [the references](/references). --- A direct reading of the Melanotan 2 photoprotection literature — the eumelanin science and the documented harms set out side by side and cited, with no clinic, no product, and no dose behind the name.